This disclosure generally relates to high-strength magnetic field processing of materials for developing customized microstructures and enhanced performance.
In powder metallurgy, powder materials are typically consolidated at high temperatures with long exposure times under applied hydrostatic loads to produce a product without porosity and with enhanced performance. For example, it is known to compact cold powder to create a semi-solid pre-form and then consolidate/mold that pre-form by applying heat and pressure. Pre-forms made from compacted powder can be placed directly upon a tool or die having a forming surface contoured to the desired shape of the completed part. In hot press forming, the pre-form is placed between matched metal tools that include forming surfaces that define the internal, external, or both mold lines of the completed part. The tools and pre-form are placed within a press and then the tools and pre-form are heated under pressure to produce a consolidated, net-shaped part.
It is known to consolidate and form pre-forms using inductively heated consolidation tools. Induction heating is a process in which an electrically conducting object (usually a metal) is heated by electromagnetic induction. During such heating, eddy currents are generated within the metal and the electrical resistance of the metal leads to Joule heating. An induction heater typically comprises an induction coil through which a high-frequency alternating current is passed. It is known to place a susceptor in or adjacent to the pre-form to achieve the necessary heating for consolidation or forming. The susceptor is heated inductively and transfers its heat principally through conduction to the pre-form sandwiched between opposing susceptor facesheets. During heating under pressure, the number of voids and/or the porosity of a pre-form can be reduced, i.e., the density can be increased.
Alloying, processing and heat treating of materials has in the past been generally limited to achieving equilibrium microstructures as defined by a temperature-composition phase diagram or metastable microstructures that result from rapid cooling processes. Recent research on ferrous alloys has shown experimentally that phase stability can be altered by applying a high-strength magnetic field to an extent that enables the microstructure of a pre-form to be tailored and precisely controlled. Combining a strong magnetic field with thermal processing can lead to the development of alloys and microstructures with superior properties
In particular, there is a need for processes that will enable rapid fabrication of near net-shaped components from powder. This includes components made of ferrous (i.e., ferrous-based) alloys having new improved chemistries along with improved affordability methods for part manufacture of titanium-based alloys